Researchers have long sought the “holy grail” of battery design – a smaller, more efficient, and cheaper battery that can charge everything from electric cars to our handheld gadgets.
Stanford University researchers have taken a huge step in this direction by designing a pure lithium anode.
The battery would benefit tremendously from a pure lithium anode. Current lithium ion batteries, however, are only partly lithium, with the lithium itself only present in the electrolyte, and not the anode.
Anodes in such batteries are made of silicon or graphite, and are prone to damage during charging, causing the formation of fissures and enabling the escape of precious lithium ions. This in turn shortens battery life.
The first challenge, therefore, is to prevent the buildup of fissures caused by this damage.
The second challenge is that a lithium anode, being chemically reactive, would use up plenty of electrolyte, thus reducing battery life.
The engineers have found a way around these issues by building nanospheres – a honeycomb-like network of carbon domes serving as a protective layer atop the lithium anode.
The nanosphere improves the battery’s coulombic efficiency – the ratio of the quantity of lithium extracted from the anode versus the amount put in when charging. The Stanford team has achieved a 99.9 percent coulombic efficiency, making their battery more efficient than the standard battery.
“While we’re not quite to that 99.9 percent threshold, where we need to be, we’re close and this is a significant improvement over any previous design,” stated researcher Yi Cui. “With some additional engineering and new electrolytes, we believe we can realize a practical and stable lithium metal anode that could power the next generation of rechargeable batteries.”